The proposed research will use multi-wave behavioral, environmental, and genetic data to test bio-psychosocial models of the joint developmental trajectories of attention deficit hyperactivity disorder (ADHD) symptoms and conduct problems in youth. Previous research has identified shared genetic and environmental risk factors for common disruptive behavior disorders (Moffitt et al., 2008; Nigg, Nikolas, & Burt, 2010; Dodge, Coie, & Lynam, 2006), including ADHD, oppositional defiant disorder (ODD) and conduct disorder (CD). ADHD symptoms and conduct problems are frequently comorbid, and functional outcomes for youth with two or more disruptive behavior disorders are significantly worse than outcomes for children with only one diagnosis (Waschbusch, 2002). Despite evidence for both environmental and genetic etiologies of disruptive behavior symptoms, little is known about the integrated roles of development, environmental stressors, and genetic risk (including gender and risk alleles) on the joint trajectories of these symptom clusters. Further, previous research on development of disruptive behaviors has concentrated on clinically referred boys. The current project will utilize hierarchical linear modeling (HLM) to test ADHD symptom severity as a predictor of conduct problems in a population sample of boys and girls, across three salient developmental periods: elementary, middle, and high school. Next, this research will test the predictive effects of time-varying family, peer and school stress, as well a negative parenting and socioeconomic status on these trajectories. Finally, the current proposal aims to replicate previous gene by environment interaction research by testing the moderating effects of three a priori identified candidate genes on stress predictors. The results of the proposed analyses will contribute significantly to the development of more individualized prevention and intervention programs for youth at risk for disruptive behavior disorders. This is directly in line with at least three areas of high priority identified by the National Institute of Mental Health Division of Translational Research: 1) test biologically based markers to improve diagnosis, identify risk indicators in order to preempt disorder, serve as criteria to personalize treatment, and evaluate treatment response; 2) test integrative models incorporating biological, behavioral and experiential factors in the development of psychopathology, and utilize longitudinal research to track trajectories of risk and protection based on the combined and interactive influences among these factors; 3) based on expanded knowledge of neurobehavioral trajectories, identify early signs of risk. Altogether, the results of the proposed analyses will fill critical gaps in scientific translational research on the development of ADHD symptoms and conduct problems in youth.